The invention is a novel branched siloxane-silalkylene copolymer containing a plurality of silicon-bonded hydrogen atoms or silicon-bonded alkoxy groups in the molecule. The copolymers are used to improve properties, such as, mechanical strength, adhesiveness, and durability of an end product.
Organosilicon polymers containing a plurality of silicon-bonded hydrogen atoms in the molecule are used as crosslinkers in hydrosilylation-based crosslinking reactions and as precursors in the synthesis of functional organosilicon polymers. Recently a desire has arisen in this area for the development of novel crosslinkers that would have higher crosslinking efficiencies and would result in the production of cured articles with excellent mechanical strength, adhesiveness, and durability properties. The result has been the appearance of a variety of organosilicon polymers that contain a plurality of silicon-bonded hydrogen atoms in each molecule (refer to Japanese Patent Application Laid Open (Kokai or Unexamined) Numbers Sho 61-195129 (195,129/1986) and Hei 6-107671 (107,671/1994)). However, even these organosilicon polymers do not provide entirely satisfactory results when used as crosslinkers or precursors.
Organosilicon polymers containing a plurality of silicon-bonded alkoxy groups in the molecule are known to be useful as raw materials for coatings, paints and as crosslinkers for moisture-curing compositions. In the last few years the need has also arisen in this area for the development of highly reactive organosilicon polymers that could be used to improve various properties such as the mechanical strength, adhesiveness, and durability of the end product.
Japanese Patent Application Laid Open (Kokai or Unexamined) Number Hei 7-17981 (17,981/1995) teaches a dendritic organosilicon polymer. The addition reaction between tetravinylsilane and organochlorosilane is disclosed for its synthesis, but the subject organosilicon polymer has little industrial utility because the precursor tetravinylsilane is a unique and highly specialized compound. In addition, while this organosilicon polymer contains silicon-bonded hydrogen, alkoxy cannot be inserted in the subject polymer by the above-described preparative method.
The present invention provides a novel branched siloxane-silalkylene copolymer that contains a plurality of silicon-bonded hydrogen atoms or silicon-bonded alkoxy groups in the molecule used to improve properties, such as, mechanical strength, adhesiveness, and durability of an end product.